I originally went to Purchase the BT-4 Assault (another great gun). The Guy @ the local PB store showed me the BT Delta brochure, told me about the "add-on" parts that were included with the Delta. Which I was planning on getting for the Assault, and I was hooked! For less than I would've spent on the Assault+add-ons. I love this marker, Very good Accuracy, even with stock Barrel (10" shorty). Even better with the 14" Empire Twister Barrel, Extremely easy to clean, disassemble, and adjust velocity. Adjustable stock and stock barrel is great for getting into tight spots. very dependable, I have yet to chop a ball, even on full auto @ 13bps. Little to heavy and slow for speedball though. Marker also has a full length Picatinny rail on top and a short rail on bottom, Lots of room for sights, scopes, lights, lasers, etc. as well as other BT accesories. E-grip is Upgradeable to a Rampage Board. Which shoots 15-25bps(i think)

Conclusion:

Very Good Overall Marker... If you like Mil-Sim markers, and play woodsball or Sim games this one's for you.